MediaPost listed some of the downsides to blog advertising, including inappropriately-targeted ads (a conservative site dumped AdWords when it showed too many ads for liberals), blog ad networks that create a homogenized cream of blog traffic without distinctive targeting handles, and a caste system among blogs where those participating in blog networks tend to leave when they find sufficient audience to strike out on their own at higher rates. All are issues that faced online advertising back at the advent of aggregated site ad networks, and the association with blogs may come up now only because of the trendiness of blogs.